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E. Common Infrastructures A Study on Long-Term Storage Techniques
for SOI-SOC MPU Wafers

Consumer-market semiconductor products can be supplied at low cost through mass production. In the space sector, however, demand is limited, and mass production creates risks of excess inventory and waste.

To address these challenges, this research aims to demonstrate a system in which wafers and chips are stored long-term before product assembly and are retrieved and assembled into final products in response to individual orders. Such a system could reduce business risks and minimize waste.

Significance of the Research

A key technical concern in long-term storage is the potential change in material and device characteristics caused by moisture absorption in low-k materials, which are widely used in modern semiconductors.
In this study, wafers and chips of the next-generation space-grade MPU (SOI-SOC4), whose development was completed in February 2025, will be used to evaluate the properties of low-k materials after approximately 10 years of storage. Through this evaluation, JAXA aims to demonstrate the feasibility of assembling products after long-term storage.

  • Enabling the on-demand supply of flight-model (FM) products
    By storing wafers and chips manufactured using mass-production technologies, the required number of flight model (FM) products can be assembled and supplied as needed.
  • Ensuring supply-chain security and stable supply through domestic storage
    By storing domestically manufactured wafers and chips within the country, production can be maintained with reduced exposure to geopolitical risks and currency fluctuations, thereby enabling a stable supply.
    Furthermore, even if wafer-fabrication lines are shut down, maintaining inventory at the wafer stage allows the supply system to remain stable.
  • Enhancing the competitiveness of Japan’s space industry
    Storing surplus wafers and chips instead of discarding them enables their reuse in future production cycles.
    In addition, optimizing quality-assurance testing for component verification can reduce costs and support stable supply, thereby strengthening international competitiveness.
Photograph of SOI-SOC4